LOS ANGELES (AP) — Leonard Nimoy didn't just leave a lasting impression on the science-fiction genre, he also left his mark on science itself.

Seth Shostak, who researches the possibility of real-world extraterrestrial life as the senior astronomer at SETI Research, recalled that Nimoy was regularly willing to lend the organization a helping hand. When he was asked to narrate a planetarium introduction or appear as a guest at an event...